Induction heating apparatus for heating the marginal edge of a disk

ABSTRACT

Induction heating apparatus for heating the marginal edge of a disk as the latter is deformed to produce a peripheral flange, incorporates ferromagnetic means located on both sides of the marginal edge of the disk, such means being adapted to move as the disk is deformed, for maintaining a relatively constant magnetic path through the marginal area of the disk during its deformation.

Pmmwww aaaazaa SHEET 1 OF 8 SHEET 3 OF 8 Fun-3mm SEP 2 0197 PATENTEDSEP 1 01974 SHEET 8 1F 8 INDUCTION HEATING APPARATUS FOR HEATING THE MARGINAL EDGE OF A DISK BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to induction heating apparatus and more particularly to such apparatus for heating the marginal area of a circular disk as it is deformed relative to the plane of the disk to provide a peripheral flange.

2. The Prior Art Electric induction heating apparatus has in the past been employed for the purpose of heating round ferromagnetic disks to the point where they become softened and may readily be deformed under pressure, to form a peripheral flange so that the disks can be used to form the bottom panels of boilers or the like. Such apparatus is disclosed in German patent application P 21 48 519.8. However, such apparatus has not been adapted to heat the disk during the process of deforming the edge. On the contrary, it has been necessary to alternately heat the disk, and then form the flange while the disk is removed from the heating apparatus. Accordingly, the apparatus described in the German patent is not wholly satisfactory because the heat rapidly dissipates during the flanging operation, with the result that the disk is not maintained at the optimum temperature during flanging.

In another known arrangement, described in Austrian pat. no. 105,313, aluminium disks have been heated continuously during flanging, but the method of doing so is restricted to the production of aluminium parts, and is not adapted for use with ferromagnetic materials.

It has not been practical heretofore to continuously heat the edge of a disk by induction, because the bending of the marginal portions of the disk demand a very large area throughout which the heating must be equally effective, if the optimum temperature is to be maintained. However, the provision of a large area is accompanied by a relatively large stray field which severely limit the useful heating energy.

Accordingly, it is desirable to provide an apparatus whereby the marginal edge of a ferromagnetic disk may be heated continuously during the time it is being deformed into a flange.

SUMMARY OF THE INVENTION A principal object of the present invention is to provide apparatus adapted for continuously heating the the effective heating zone moves as the edge of the disk is deformed.

These and other objects and advantages of the invention will become manifest upon an examination of the following description and the accompanying drawings:

In one embodiment of the present invention there is provided induction heating apparatus having ferromagnetic members located on both sides of the marginal zone of a circular disc, the ferromagnetic members being movable as the disk is deformed for maintaining close magnetic association with the surface of said disk during the deformation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view of apparatus incorporating an illustrative embodiment of the present invention;

FIG. 2 is a cross-sectional view of a portion of the apparatus of FIG. 1, taken in theplane Il-II;

FIG. 3 is a cross-sectional view of a portion of the apparatus of FIG. 1, taken in the plane III-III;

FIG. 4 is a cross-sectional view of apparatus incorporating an alternative embodiment of the present invention;

FIG. 5 is a cross-sectional view of apparatus incorporating another embodiment of the present invention;

FIG. 6 is a cross-sectional view of apparatus incorporating a further embodiment of the present invention;

FIG. 7 is a diagramatic view showing, at four different phases, the change in position of apparatus incorporating yet a further embodiment of the present invention during four successive phases in the deformation of a disk; and

FIG. 8 is a plan view of apparatus incorporating yet another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, the round disk 1 is supported (by means not shown) for rotation about a vertical central shaft (not shown). The disk 1 is shown in undeformed condition, and after the heat deformation it has an upwardly directed flange l. The heating of the marginal zone of the round disk 1 is accomplished before and during the deformation by means of an inductor 2, having an upper leg 3, and a lower leg 4. The upper leg 3 is arched upwardly so as to accommodate in this arch 5 the deformed edge 1' of the round disk. The upper leg 3 and the lower leg 4 are interconnected by a hinge 6, so that the inductor can be opened into the position shown in broken lines in FIG. 1, and thus be moved away more easily from the edge of the round disk when the deformation is concluded, or when an additional deformation is intended for which the arch 5 of the upper leg 3 is insufficient. Such a hinged inductor may be moved out of the area of the marginal zone of the disk 1 after opening in the manner described in German patent application No. P 21 48 519.8.

Alternatively, the inductor 2 may be of rigid design, without the hinge 6. In that case, it is moved in the direction of the arrow 7 away from the marginal zone, when desired, as described in the aforementioned German patent.

Electrical current is supplied to the inductor 2 through the terminals 8 and 8, which are connected to the conductors 9 of the upper and lower legs 3 and 4, respectively. Each conductor 9 has a generally rectangular cross-section, as seen in FIG. 2, and is preferably formed of copper and is provided with passages (not shown) for water cooling. The construction of the conductors 9 may be the same as that described in the aforementioned German application. Each conductor 9 is partially surrounded by short circuit panel 10, for concentration and guidance of the magnetic flux, the short circuit panel comprising, in FIG. 2, a ferromagnetic U-shaped panel 11.

The conductors 9 are supported rigidly relative to the center of the disk 1, and the shape of conductor 9 in the lower leg 4 of the inductor conforms to the plane shape of the undeformed marginal zone. The conductor 9 in the upper leg 3 conforms to the shape of the deformed marginal zone 1. The result is that the conductor 9 of the upper inductor leg 3 has, prior to the deformation, a larger distance from the disk 1, and after the accomplished deformation of the marginal zone of the round disk, a smaller distance, as compared with the conductor 9 of the lower inductor leg 4. In order to achieve equal heating on both surfaces of the round disk 1, the ferromagnetic panels 10 are arranged at least in part of an angle of about 45 to the horizontal line. The panels 10 are supported in fixed relation to the inductor body, where the deformation is small, and the upper and lower legs 3 and 4 are not widely separated from each other, especially toward the central portion. The panels 11, shown in FIG. 2, which shows the cross section toward the central portion of the disk 1, are preferably formed of sheets of ferromagnetic material, with adjacent sheets being insulated from each other, to minimize eddy current losses. The panels 11 are preferably about 0.3 mm thick and are positioned closely adjacent each other. 1

FIG. 3 shows a cross section at a point spaced radially outward relative to FIG. 2. As shown in FIG. 3, certain portions of the short circuit panels 10 are movable. In particular, the parts 12 and 12 and 14 and 14 are movable toward and away from the disk 1, while the center parts 13 and 13 of. the ferromagnetic short circuit panels 10 are supported in fixed relation. The round disk 1, and the movable panels 12, 12', 14 and 14' are shown in broken lines, to illustrate their positions before deformation, while the round disk 1' and the movable panels are shown in solid lines to illustrate their positions after deformation. Because of the movable panels, the magnetic flux, within the disk 1, is relatively constant during deformation of the disk 1. The flux path within the disk 1 is identified by reference numeral 15 before deformation, and after deformation by 15. As a result, the disk 1 is heated approximately evenly on both sides, during deformation. The movement of the parts 12, 12 and 14, 14 in the direction of the arrows 16-19 is controlled by non-magnetic rollers or sliding parts 20, 20', 21, 21 which contact the marginal zone of the round disk 1. The sliding parts are preferably formed of a ceramic material or the like. The deformation of the marginal portion of the disk 1 is performed, during heating, by pressure applied by hydraulic or pneumatic means.

FIG. 4 represents several loop arms A to C of the upper inductor leg 3, with their ferromagnetic panels in the position they occupy prior to the deformation of the edge of the round disk 1. The individual parts of the ferromagnetic panels have the same reference symbols as in FIG. 3. A bracket 41 is provided for moving the ferromagnetic panels 12 and 12'. The bracket 41 is urged rightwardly, as viewed in FIG. 4, so that projections 20 bear upon the marginal zone of the disk. The bracket 41 is also effective to return the moving parts 12 and 12', following deformation and removal of the deformed round disk, back into their starting positions. The bracket 41 is provided with non-ferromagnetic members 24 for supporting the movable parts 12 and 12. In addition, an electrical insulation member 25 is provided between the movable parts 12 and 12' and the member 24. Water-cooled copper panels 26 are provided for cooling the movable parts 12 and 12'. The projections 20 and 20' are preferably formed of ceramic material, and insulate the disk 1 from the copper panels 26.

FIG. 5 shows a portion of an assembly provided for the lower inductor leg 4, employing a different arrangement for supporting and guiding the movable parts 14. The upper inductor leg 3 (not shown) is of analogous design. The stationary parts 13 of the ferromagnetic panels 10 are arranged in arcuate fashion, and the movable parts 14 are provided with rollers 21 formed of non-ferromagnetic material. The movement of the parts 14 is accomplished by the pressure of compression springs 27, which bear against a bracket 28 made of insulating material. The movable parts 14 can be re tracted against the pressure of springs 27 by means of a tension bar 29, in order to accommodate a new (undeformed) disk. The movable parts 14 are guided by bushing 30, made of insulating material, for rectilinear movement toward, and away from the disk 1.

FIG. 6 shows another embodiment, in which the disk 1 rotates in the direction of the arrow. The conductors 9 of the upper leg 3 and the lower leg 4 are both provided with passages 9a to support a flow of water for cooling, and are disposed adjacent to the stationary ferromagnetic parts 13 and 13. The movable parts 12, 12 and 14, 14 are preferably covered with water-cooled copper panels such as the panels 26 of FIG. 4, which panels are insulated by mica foil from the movable parts of the circuit, and which are also used to guide the movable parts 12, 12, 14 and 14'. The movable parts are also guided by bushings 30 and 30, which are formed of insulating material.

The movable parts 12, 12, 14 and 14 are interconnected by transverse rods 24 and 24". The rod 24' is connected to a tension spring 31, for equalization of the weight of the assembly to relieve some of the weight from the rollers or sliding parts 20 and 20. In the lower inductor leg 4, a compression spring 27 urges the assembly upwardly against the rod 24". The movable parts 14 and 14 can be returned to their starting position by compressing the spring 27 and holding it in compressed condition by means of a latch wheel 32, having a hook engaging the lower end of a rod 29, the upper end of which is connected to the rod 24". This is done prior to the introduction of the next round disk to be deformed. The latch wheel 32, the lever 33, the bar 29 and the compression spring 27 are shown in tensioned position, that is after the return operation. Alternative means may be used in lieu of springs, such as hydraulic and pneumatic actuators, or the like.

FIG. '7 shows a tunnel-like inductor adapted to be placed at the edge of the round disk and slide thereon by means of non-magnetic, sliding parts 37. Rollers may be substituted for the sliding parts 37 if desired. The inductor 35 is provided at 36 with leads by which electrical power is applied thereto, and it is supported by a line 34 having an end secured to a weight 38 over a pair of rollers 39 and 40. The roller 40 is displaceable horizontally, over a path a.

A coiled current-bearing conductor is supported within the inductor 35. The tunnel inductor 35 is maintained at a distance from the surfaces of the round disk by the sliding parts 37, and stationary ferromagnetic members may be provided to establish a path for magnetic flux through the marginal portion of the disk 1. The length of the tunnel inductor 35 in the circumferential direction of the round disk 1 may be increased with increasing diameter of the round disk and with decreasing angle alpha of deformation. Several tunnel inductors 35 also may be juxtaposed at different positions on the circumference of the round disk. The four views of FIG. 7 represent the relative positions of the apparatus at four different phases in the deformation of a disk. In the first phase, the deformation is slight, and the position of the roller 40 is adjacent the roller 39. Then the roller 40 is moved rightwardly progressively, as the deformation is increased, so that the inductor 35 remains aligned with the edge margin of the disk.

FIG. 8 shows an assembly employing two inductors, 2 and 35, arranged in series on the circumference of the round disk 1. The central part of the marginal zone is heated with the aid of the inductor 2, while the tunnel inductor 35 heats the outer marginal area.

The present invention is effective to maintain a constant heating of the marginal portion of a disk while it is being deformed, and it is not necessary for the heating to be discontinued as the deformation is performed. The use of the laminated panels permits the apparatus to operate efficiently, and only a small amount of energy is lost in the ferromagnetic panels. The air gaps between the ferromagnetic panels and the disk are maintained small, so the magnetic flux in the disk 1 is maximized, and little energy is lost due to stray magnetic fields.

If desired, the movable ferromagnetic panels of the present invention may be moved manually, or by the use of motors or the like, instead of by springs as described above.

What is claimed is:

1. Induction heating apparatus for heating the marginal edge of a disk while it is being deformed into a flange, flux generating means for establishing a magnetic flux within said marginal edge, means for maintaining said magnetic flux in approximately the same concentration in said marginal edge throughout said deformation, separate flux generating means disposed on opposite sides of the marginal edge of said disk for uniformly heating both of said sides and means supporting said separate flux generating means for movement in the same relative direction as said edge is deformed.

2. Apparatus according to claim 1, wherein said supporting means includes a compression spring on one side of said disk and a tension spring on the other side of said disk.

3. Apparatus according to claim 1, wherein said flux generating means includes a ferromagnetic member and an electrical conductor, and including electrical insulating means interposed between said ferromagnetic member and said conductor.

4. Apparatus according to claim 1, wherein said flux generating means includes a ferromagnetic member and an electrical conductor, and electrical insulating means interposed between said ferromagnetic member and said disk.

5. Induction heating apparatus for heating the marginal edge of a disk while it is being deformed into a flange, flux generating means for establishing a magnetic flux within said marginal edge, means for maintaining said magnetic flux in approximately the same concentration in said marginal edge throughout said deformation, separate flux generating means disposed on opposite sides of the marginal edge of said disk, for uniformly heating both of said sides, means supporting said separate flux generating means for movement in the same relative direction as said edge is deformed, said flux generating means comprising two separate inductors each juxtaposed with a separate minor proportion of the periphery of said disk, one of said inductors being adapted for heating the central portion of the marginal zone of said disk, and the other inductor being adapted for heating the outer portion of said marginal zone.

6. Apparatus according to claim 5, wherein said one inductor is provided with a movable ferromagnetic member means for moving said movable member to maintain an end of said movable member juxtaposed with said disk, and wherein said second inductor is a tunnel inductor.

7. A method of heating the marginal edge of a disk while it is being deformed into a flange, comprising the steps of establishing a magnetic flux within said marginal edge, maintaining said magnetic flux in approximately the same concentration throughout said deformation, providing a path for said magnetic flux including a movable ferromagnetic member, moving said member during said deformation to maintain a constant spacing between said movable member and said disk, movable ferromagnetic members being provided on opposite sides of said disk, and wherein the movable members on both sides of said disk are moved during said deformation to maintain a relatively constant separation between said disk and said movable members.

8. An apparatus for heating the edge zone of a disc, for example, a boiler bottom or the like rotating repeatedly about a central normal axis of the disc for the purpose of deformation of the edge zone to form a marginal rim, comprising an edge heating tool, alternating current inductors cooperable with the edge tool which sectorially impinge on both sides of the disc, the inductors including current conductors which enclose the edge zone of the disc before and during the deformation, first means provided for movement on said edge heating tool for the concentration of the magnetic alternating field, and support means for movably guiding said first means in the area of the edge zone in such a manner that in each phase of the deformation the inductors and the disc are operatively coupled.

9. Apparatus according to claim 8 further characterized in that the first means comprises movable shortcircuit panels, and rollers supporting said panels on the disc, said support means including means having the panels extended there through.

10. Apparatus according to claim 9 further comprising a pressure equalizer connecting said support means with one another.

11. Apparatus according to claim 8, characterized in that the first means comprises movable short-circuit panels which are electrically insulated from the windings of the conductors.

disc and being further provided with the movable shortcircuit panels, said short-circuit panels including iron, said apparatus further comprising rollers and the second of said inductors being constructed as a short tunnel inductor and being movable during the deformation and operable to continuously heat the outer part of the edge zone while traveling on said rollers. 

1. Induction heating apparatus for heating the marginal edge of a disk while it is being deformed into a flange, flux generating means for establishing a magnetic flux within said marginal edge, means for maintaining said magnetic flux in approximately the same concentration in said marginal edge throughout said deformation, separate flux generating means disposed on opposite sides of the marginal edge of said disk for uniformly heating both of said sides and means supporting said separate flux generating means for movement in the same relative direction as said edge is deformed.
 2. Apparatus according to claim 1, wherein said supporting means includes a compression spring on one side of said disk and a tension spring on the other side of said disk.
 3. Apparatus according to claim 1, wherein said flux generating means includes a ferromagnetic member and an electrical conductor, and including electrical insulating means interposed between said ferromagnetic member and said conductor.
 4. Apparatus according to claim 1, wherein said flux generating means includes a ferromagnetic member and an electrical conductor, and electrical insulating means interposed between said ferromagnetic member and said disk.
 5. Induction heating apparatus for heating the marginal edge of a disk while it is being deformed into a flange, flux generating means for establishing a magnetic flux within said marginal edge, means for maintaining said magnetic flux in approximately the same concentration in said marginal edge throughout said deformation, separate flux generating means disposed on opposite sides of the marginal edge of said disk, for uniformly heating both of said sides, means supporting said separate flux generating means for movement in the same relative direction as said edge is deformed, said flux generating means comprising two separate inductors each juxtaposed with a separate minor proportion of the periphery of said disk, one of said inductors being adapted for heating the central portion of the marginal zone of said disk, and the other inductor being adapted for heating the outer portion of said marginal zone.
 6. Apparatus according to claim 5, wherein said one inductor is provided with a movable ferromagnetic member means for moving said movable member to maintain an end of said movable member juxtaposed with said disk, and wherein said second inductor is a tunnel inductor.
 7. A method of heating the marginal edge of a disk while it is being deformed into a flange, comprising the steps of establishing a magnetic flux within said marginal edge, maintaining said magnetic flux in approximately the same concentration throughout said deformation, providing a path for said magnetic flux including a movable ferromagnetic member, moving said member during said deformation to maintain a constant spacing between said movable member and said disk, movable ferromagnetic members being provided on opposite sides of said disk, and wherein the movable members on both sides of said disk are moved during said deformation to maintain a relatively constant separation between said disk and said movable members.
 8. An apparatus for heating the edge zone of a disc, for example, a boiler bottom or the like rotating repeatedly about a central normal axis of the disc for the purpose of deformation of the edge zone to form a marginal rim, comprising an Edge heating tool, alternating current inductors cooperable with the edge tool which sectorially impinge on both sides of the disc, the inductors including current conductors which enclose the edge zone of the disc before and during the deformation, first means provided for movement on said edge heating tool for the concentration of the magnetic alternating field, and support means for movably guiding said first means in the area of the edge zone in such a manner that in each phase of the deformation the inductors and the disc are operatively coupled.
 9. Apparatus according to claim 8 further characterized in that the first means comprises movable short-circuit panels, and rollers supporting said panels on the disc, said support means including means having the panels extended there through.
 10. Apparatus according to claim 9 further comprising a pressure equalizer connecting said support means with one another.
 11. Apparatus according to claim 8, characterized in that the first means comprises movable short-circuit panels which are electrically insulated from the windings of the conductors.
 12. Apparatus according to claim 11, further characterized in that the movable short-circuit panels are electrically insulated from the disc.
 13. Apparatus according to claim 8, wherein said alternating current inductors comprises two inductors and further characterized in that the two inductors are arranged consecutively in the direction of movement of the disc, a first of said inductors being operable to heat the part of the edge zone nearest to the interior of the disc and being further provided with the movable short-circuit panels, said short-circuit panels including iron, said apparatus further comprising rollers and the second of said inductors being constructed as a short tunnel inductor and being movable during the deformation and operable to continuously heat the outer part of the edge zone while traveling on said rollers. 